U.S. patent number 4,835,042 [Application Number 07/049,983] was granted by the patent office on 1989-05-30 for absorbent member.
This patent grant is currently assigned to KAO Corporation. Invention is credited to Norihiro Abe, Masatake Dohzono, Iwao Miyashita.
United States Patent |
4,835,042 |
Dohzono , et al. |
May 30, 1989 |
Absorbent member
Abstract
An absorbent member, suitable for a tampon, is produced by
ejecting a liquid against a sheet of water-absorptive fibers in
order to interlace the fibers with each other and molding under a
pressure the sheet to form the absorbent member.
Inventors: |
Dohzono; Masatake (Utsunomiya,
JP), Miyashita; Iwao (Utsunomiya, JP), Abe;
Norihiro (Utsunomiya, JP) |
Assignee: |
KAO Corporation (Tokyo,
JP)
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Family
ID: |
26347818 |
Appl.
No.: |
07/049,983 |
Filed: |
May 15, 1987 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
Issue Date |
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816860 |
Jan 7, 1986 |
4714466 |
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Foreign Application Priority Data
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Jan 25, 1985 [JP] |
|
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60-12244 |
Jan 25, 1985 [JP] |
|
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60-12247 |
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Current U.S.
Class: |
428/218; 264/517;
28/104; 28/118; 428/913; 442/408 |
Current CPC
Class: |
A61F
13/2051 (20130101); A61F 13/2085 (20130101); D04H
1/492 (20130101); Y10S 604/904 (20130101); Y10T
442/689 (20150401); Y10T 428/24992 (20150115); Y10S
428/913 (20130101) |
Current International
Class: |
A61F
13/20 (20060101); D04H 1/46 (20060101); B32B
007/02 () |
Field of
Search: |
;604/378,379,380,286,DIG.904 ;28/104,105,118 ;428/913,218,299
;264/121,517 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Bell; James J.
Attorney, Agent or Firm: Birch, Stewart, Kolasch &
Birch
Parent Case Text
This application is a divisional of copending application Ser. No.
816,860, filed on Jan. 7, 1986, now U.S. Pat. No. 4,714,466.
Claims
The embodiments of the invention in which an exclusive privilege or
property is claimed are defined as follows:
1. A process for producing an absorbent member having a front part
and a rear part, said front part having a first fiber portion and
said rear part having a second fiber portion, said first fiber
portion having a smaller fiber density than said second fiber
portion, which comprises the steps of ejecting a liquid against a
sheet of water-absorptive fibers at an ejection pressure of at
least 10 kg/cm.sup.2 in order to interlace the fibers with each
other; and compression molding said sheet under sufficient pressure
to form the absorbent member.
2. An absorbent member having a front part and a rear part, which
comprises a first fiber portion on the front part and a second
fiber portion on the rear part, said first fiber portion having a
smaller fiber density than said second fiber portion, said member
having been produced by ejecting a liquid against a sheet of
water-absorptive fibers at an ejection pressure of at least 10
kg/cm.sup.2 in order to interlace the fibers with each other and
compression molding said sheet under sufficient pressure to form
the absorbent member.
3. An absorbent member as claimed in claim 2 wherein said first
fiber portion has a fiber density of no greater than 0.5 g/cm.sup.3
on the average and said member on the whole has a fiber density of
no greater than 0.7 g/cm.sup.3 on the average.
4. An absorbent member as claimed in claim 2, wherein said first
fiber portion occupies a volume of from 30 to 70 percent.
Description
The invention relates to an absorbent member for a tampon and a
sanitary article for women needing the same. It further concerns a
process for production of the absorbent member.
STATEMENT OF PRIOR ARTS
It is known that a tampon is produced, for instance, by cutting a
laminated sheet of water absorptive fibers into rectangle pieces,
attaching a pulling-out string to each piece and moulding the piece
under a pressure to a tampon. In another production a web sheet of
water-absorptive fibers is wound to form a volute cylinder and
moulded under a pressure to a tampon. After use of such a
conventional tampon, however, some fibers disadvantageously happen
to fall off by contact and frictional resistance of the swollen
tampon due to absorption of menstrual blood on the vaginal
wall.
With a view to reducing the amount of a fiber falling off, a method
of integration of a fiber laminate by needling is disclosed in
Japanese Patent Laid-Open No. 59498/1974. According to this method,
mutual interlacing of the fiber is improved. However, the fiber is
so damaged because of needling with a metallic needle as to locally
form short fibers. Thus the effect of reducing the amount of the
falling fiber is not sufficient. Besides, a needle is sometimes
broken and incorporated into a tampon in the molding thereof. Thus
such a tampon is very dangerous as a sanitary disposal article to
be used by inserting the same into a vagina. Thus this method in
regrettably inadequate as the method of integration of the fiber
laminate.
A proposal as to attachment of a pull-out string has been made in
Japanese Utility Model Publication No. 25,376/1984. However, the
method is unsatisfactory particularly from the viewpoint of falling
off of minute fibers (fiber dust) and a short fibers.
Further, Japanese Utility Model Publication No. 25,377/1984
discloses a device aimed at achieving the same purpose as that of
this invention. However, since a hydrophobic fiber is disposed
around the peripheral surface of a tampon, there arises a defect
that the rate of absorption is lowered for a high viscosity liquid
such as menstrual blood.
A slow rate of absorption of a high viscosity liquid such as
menstrual blood as mentioned above is a common problematic defect
among conventional tampons. This generally ensues from the
menstrual blood absorption inhibiting properties of a lubricant
(finishing agent) and impurities in the step of fiber manufacturing
which stick to the water-absorptive fibers constituting the
absorbent member of a tampon. The absorbent member of a tampon
generally comprises a water-absorptive fiber, such as rayon, as the
constituent material. However, a lubricant is applied to such a
fiber allowing the steps of spinning, knitting, dyeing, etc. to be
easily practiced. More specifically, the lubricant is employed for
satisfying the requirements such as flexibility, smoothness,
adequate frictional properties, and antistatic properties. In spite
of the above, it has been found that the rate of absorption is, in
general, increased when a tampon is formed by using a fiber
laminate containing decreased amounts of a lubricant and impurities
by water washing thereof or the like. Accordingly, it can be
concluded that the absorption rates of conventional tampons are
slowed by a lubricant, etc. sticking to a fiber, which is necessary
for manufacturing and processing of a fiber laminate.
In general, this kind of tampon, which is formed by
compression-molding a water absorptive fiber into a cylindrical
shape, gradually absorbs menstrual blood from the tip portion
thereof to be gradually swollen from the tip portion when it is
inserted into a vagina. However, since the tampon is
compression-molded with a amount of the fiber large enough to have
a high fiber density for providing a sufficient capacity of
absorption of menstrual blood and facilitating insertion thereof
into a vagina, the rate of absorption of menstrual blood is slow
with a difficulty in swelling, so that menstrual blood may
sometimes leak along the side of the tampon.
An invention aiming at obviating such defects is disclosed in
Japanese Patent Publication No. 17,583/1980. A known method
disclosed therein is characterized in that it provides a density of
0.2 to 0.8 g/cm.sup.3 in the tip portion of the absorbent member of
a tampon, a density of 0.8 to 1.5 g/cm.sup.3 in the rear portion of
the member, and a length of the tip portion of 1/10 to 1/2 the
total length of the absorbent member of a tampon. However, although
a tampon produced according to this known method surely has a high
rate of absorption and a high capacity of absorption for a
low-viscosity liquid such as water, the tampon does not have a
sufficiently high rate of absorption for a high-viscosity liquid
such as menstrual blood. Thus, the method can not obviate the
defects of the conventional absorbent member of a tampon as
mentioned above. This is because a lubricant (finishing agent) such
as rayon is generally applied to a water-absorptive fiber, as, and
employed in the absorbent member of a tampon, leading to occasional
obstruction of absorption of menstrual blood, and because the fiber
density of 0.8 to 1.5 g/cm.sup.3 in the rear portion is too high,
leading to a difficulty in absorption of menstrual blood. The
purpose of application of a lubricant to a fiber is to satisfy
various purposes such as spinning, knitting, dyeing, and antistatic
treatment. Thus application of the lubricant is indispensable from
the viewpoint of processability.
The conventional absorbent member of a tampon is generally produced
according to, for example, a method comprising compression-molding
a loose fiber piece, such as a fiber web, having a basis weight of
about 300 to 1,000 g/m.sup.2 in the diametrical and lengthwise
directions thereof either as it is or after it is folded, or a
method comprising compressing the fiber web, having a basis weight
of about 40 g/m.sup.2 in the diametrical direction thereof after it
is rolled into a volute form. However, since the fiber web
generally contains minute fibers (fiber dust) and short fibers of
10 mm or less in length and has a low degree of mutual fiber
interlacing, there is a defect that the fiber falls off and remains
in the vagina when the tampon is pulled out after service thereof.
More specifically, part of the fiber constituting the absorbent
member of the tampon, particularly part of the fiber constituting
the peripheral surface of the tampon, defectively falls off and
remains in the vagina by contact of the swollen tampon due to
menstrual blood and/or when inserted into the vagina the vaginal
wall provides frictional resistance when pulling out the
tampon.
As described above, conventional sanitary tampons have the
following defects.
(1) The amount of a fiber falling off when pulling out a tampon
after service is large.
(2) The rate of absorption of a high-viscosity liquid such as
menstrual blood is small.
SUMMARY OF THE INVENTION
According to the invention, an absorbent member, suitable for a
tampon, is produced by the steps of ejecting a liquid against a
sheet of water-absorptive fibers in order to interlace the fibers
with each other and moulding, under a pressure, the sheet to form
the absorbent member. The ejection step makes the water-absorptive
fibers, having been formed into a sheet, interlace with each other,
coil around each other, get twisted, cling to each other or
entwine. The invention provides an absorbent member which has been
produced by the above defined process. A preferable embodiment of
the absorbent member according to the invention comprises a first
portion on the front part and a second portion on the rear part,
said first portion having a smaller fiber density than the second
portion.
Specifically, in accordance with the present invention, there is
provided an absorbent member of a tampon characterized in that it
is formed by ejecting a liquid against a fiber laminate mainly
comprising a water-absorptive fiber to interlace the fiber and
compression-molding the resulting sheet-like material.
BRIEF DESCRIPTION OF THE DRAWINGS
FIGS. 1 and 2 are rough crossectional illustrations of processes of
preparation of the fiber sheet-like material to be employed in the
absorbent member of a tampon according to the present invention.
FIGS. 3, 5, and 6 are perspective views showing the state of
compression-molding fiber sheet-like materials. FIG. 4 is a
perspective view of an example of a fiber sheet-like material in
accordance with the present invention. FIGS. 7 and 8 are
perspective views showing examples of other shapes for tampons.
FIGS. 9 to 12 illustrates a preferable embodiment of the invention
absorbent member which comprises the first and the second portions.
FIG. 9 shows a preferable example of a sheet of fibers to use in
the invention. FIG. 10 shows an example of the invention tampon in
the front view. FIG. 11 shows another example of a sheet of fibers
to use in the invention. FIG. 11 (a) illustrates the state before
the ejection and (b), the state after the ejection treatment. FIG.
12 also indicates an example of a sheet of fibers to use in the
invention.
1: fiber laminate
2, 2', 2": arrow showing the direction of ejection of ejection of a
liquid
3: fiber sheet-like material
4: belt
5, 5': rectangular fiber sheet
6: central portion
7: string
8: portion having a low degree of interlacing
9: portion having a high degree of interlacing
10: fiber sheet-like material having a low degree of
interlacing
11: fiber sheet-like material having a high degree of
interlacing
12: water-absorptive fiber laminate
13: water-absorptive fiber web
14: fiber sheet having a relatively light basis weight
15: drying apparatus
16: laminate of sheets of fibers
17: sheet of fibers
m: the second part of the absorbent member
n: the first part of the absorbent member
In this invention, a fiber web mainly comprising a water-absorptive
fiber is formed by a spinning card, a garnett or other apparatus. A
fiber laminate is obtained by laminating the fiber web either as
such or by using an adequate method. Methods of lamination of a
fiber include one wherein fibers are arranged substantially in
parallel in the lengthwise direction of the web (parallel-laid
lamination) and one wherein fibers are arranged by folding the web
(cross-laid lamination). A fiber laminate 1 as shown in FIG. 1 is
formed by one of these methods. The fiber laminate may be obtained
according to a method of non-directional random arrangement
(air-lay) of a fiber.
The fiber laminate 1 thus obtained is transferred on a belt 4 to a
liquid ejection step. In the liquid ejection step, a liquid is
ejected against the fiber laminate 1 in a direction of an arrow 2
as shown in FIG. 1. The liquid is generally water. However, heated
water such as warm water or hot water may sometimes be effective
for the purpose of washing out a lubricant and other impurities
sticking to the fiber in accordance with the present invention.
After ejection of the liquid in this way, the fiber laminate was
dried in a drying apparatus 15 to form a fiber sheet-like material
3 in which the fiber is interlaced. In the present invention, the
degree of interlacing of the fiber constituting the fiber laminate
is significant, and washing out the lubricant sticking to the fiber
is important. The key point of attaining the above is the ejection
pressure of the liquid. More specifically, the ejection pressure is
preferably 10 kg/cm.sup.2 or higher. A fiber sheet prepared at a
pressure below the above value is so low in the degree of fiber
interlacing that the amount of the fiber falling off in compression
molding of a tampon may be large, and that the effect of washing
out the lubricant cannot be expected so much. Besides, the effect
of removing a minute and/or short fiber contained in the fiber
laminate is unsatisfactory. Here, the short fiber generally refers
to a fiber of 10 mm or less in length. The kind of water-absorptive
fiber constituting the fiber laminate may be any one of those
generally used in tampons, such as rayon, dewaxed cotton, or a
mixture thereof. A small amount of a hydrophobic fiber may be
blended therewith. The fiber size is not particularly limited.
However, a size of about 1 to 5 deniers is adequate from the
viewpoint of water absorption performance as the fiber used in
tampons. A fiber length of 20 mm or more, especially 30 mm or more,
is adequate for the purpose of reducing the amount of the fiber to
fall off in accordance with the present invention.
The basis weight of the fiber laminate 1 against which the liquid
is ejected depends on the shape of tampons obtained by compression
molding but is not particularly limited.
In the above-mentioned method of interlacing a fiber by ejecting a
liquid there against, the degree of fiber interlacing may sometimes
be affected by the shape, etc. of a nozzle used for liquid
ejection. However, in preparation of a water-absorptive fiber
sheet-like material according to the present invention, any shape
of a nozzle may be employed. Besides, a method of ejecting a liquid
simultaneously in different directions 2, 2', and 2" as shown in
FIG. 2, and a method of simultaneously or separately ejecting a
liquid against the fiber laminate 1 from both the upper and lower
sides thereof can be mentioned as the method of efficiently
conducting fiber interlacing.
Further alternatively, a fiber sheet-like material to be
compression-molded into the absorbent member of a tampon according
to the present invention may be obtained according to a method of
ejecting a liquid against a fiber laminate superimposed on a
non-woven fabric mainly comprising a water-absorptive fiber as a
base cloth or a fiber laminate sandwiched between such base cloths
in the same manner of ejection as shown in FIG. 1 or 2. The sheet
thus obtained has a merit that it has an increased strength enough
to make handling thereof easy since it comprises the non-woven
fabric.
As an example of the method of compression-molding the fiber
sheet-like material in accordance with this invention, there can be
mentioned a method comprising crosswise laminating two pieces of
rectangular absorbent fiber sheets 5 by cutting an absorbent
sheet-like material into an adequate size, attaching a string 7 to
the laminate in the central portion 6 thereof in such a way as to
allow the string to protrude in that portion as the rear end, and
compression-molding the assembly, as shown in FIG. 3. The absorbent
member of a tampon thus obtained opens like a parachute due to
swelling thereof when it absorbs menstrual blood. Thus, menstrual
blood hardly leaks. Besides, the tampon is characteristically
easily pulled out after service thereof. In compression molding of
a tampon according to the method as shown in FIG. 3, there may be
employed a fiber sheet 5' as shown in FIG. 4 which is subjected to
much repeated ejection of a liquid on one side 9 thereof and to no
ejection or a few ejections of a liquid on the other side 8
thereof. In this case, since there is a difference in the degree of
fiber interlacing between the obverse side and reverse side of the
fiber sheet, compression molding conducted after lamination as
shown in FIG. 3 is made in such a way that the side 8 having a low
degree of fiber interlacing is disposed on the inner side of the
tampon while the side 9 having a high degree of fiber interlacing
is disposed on the outer side of the tampon. In this instance, a
difference in the frequency of ejection is provided between both
the sides of the fiber laminate. The same purpose can be attained
by providing a difference in the pressure of ejection between both
sides.
In another instance, a fiber sheet 11 having a high degree of
interlacing and a fiber sheet 10 having a low degree of interlacing
may be prepared and laminated in such a way as to dispose the fiber
sheet 10 having the low degree of interlacing on the inner side of
a tampon as shown in FIG. 5, followed by compression molding.
In still another instance shown in FIG. 6, a fiber sheet 14 having
a relatively light basis weight is prepared, and a large number of
pieces of the sheet is alternately superimposed, as shown in FIG.
3, followed by compression molding. In this case, the tampon
obtained easily opens when absorbing menstrual blood due to a large
repulsive force of the fiber. Alternately, ejection of a liquid for
fiber interlacing may be conducted after superimposition of pieces
of a fiber laminate as shown in FIG. 3, followed by compression
molding.
The feature of the absorbent member of a tampon according to the
present invention consists in use of a fiber sheet-like material
subjected to ejection of a liquid to effect fiber interlacing.
Thus, those having a shape as shown in FIG. 7 or 8 are included in
the scope of this invention. Further, the absorbent member of a
tampon according to this invention which is mounted on a so-called
applicator is included in the scope of this invention, too.
Since the absorbent member of a tampon according to the present
invention is high in the degree of fiber interlacing and low in the
content of short fiber at least on the outer side of the absorbent
member of the tampon in contact with a vaginal wall, falling off of
the fiber hardly occurs when pulling out the tampon swollen by
absorption of menstrual blood during or after service thereof.
Furthermore, since the amount of lubricant sticking to the fiber is
small, the rate of absorption of a high-viscosity liquid such as
menstrual blood is high. Particularly, the absorbent member of a
tampon obtained by laminating the fiber sheet 5' as shown in FIG. 4
in a way as shown in FIG. 3 and compression-molding the same
provides an ideal tampon having a large capacity of absorption
which hardly allows leakage.
Then, the invention will be illustrated in respect to a preferable
embodiment in which the absorbent member has different fiber
densities therein.
Before the compression-moulding step, an absorbent member of the
invention is shown in FIGS. 7 and 8. The second part, 12m, 13m, for
the rear portion of the absorbent member, hatched in the drawing,
has a higher fiber density than the other part. In comparison, the
first part 12n, 13n for the front portion of the absorbent member,
which will first contact with menstrual blood when the tampons are
inserted into vaginas, are lower in fiber density. In order to
provide a high fiber density and a low fiber density in the fiber
laminate to be compression-molded into the absorbent member of the
tampon, the ejection pressure of a liquid against the fiber
laminate only has to be varied between portions of the fiber
laminate. Thus, the portion subjected to ejection at a high
pressure can be made high in fiber density, while the portion
subjected to ejection at a low pressure can be made low in fiber
density. Alternatively, the number liquid ejections against the
fiber laminate may be varied between portions of the fiber laminate
to provide a high fiber density in the portions subjected to a
large number of ejections and a low fiber density in the portion
subjected to a small number of ejections.
FIG. 9 shows an example of the sheet of fibers in which the fibers
have been interlaced with one another according to the above shown
step. It is attached to a string as shown in FIG. 7 in the
direction of A and A' and then moulded under a pressure to form a
tampon as shown in FIG. 10.
According to the method, the portion n having a low fiber density
in the sheet gets thicker, while the portion m having a high fiber
density gets thin. This is shown in FIG. 9. This is favorable for
the tampon, because the tampon can be easily pulled out due to a
smaller volume of the rear portion of the tampon than that of the
front portion thereof when pulling out the tampon after service
thereof since the absorbent member of the tampon, which is a
compressed product of fiber, has a tendency of returning, upon
absorption of menstrual blood, to the original shape of the fiber
sheet-like material before absorption of menstrual blood.
The second method of providing high and low fiber densities is a
method comprising superimposing fiber laminates 16, 16' and 16"
having adequate basis weights as shown in FIG. 11(a) and ejecting a
liquid against the resulting laminate to form a fiber sheet-like
material having a substantially uniform thickness as shown in FIG.
11(b). Since the hatched portion m has a high fiber density while
the other portion n has a low fiber density according to this
method, the absorbent member of the produced tampon has a high rate
of absorption in the tip portion thereof.
Another Example will now be described. A rectangular sheet of
fibers is formed to have a lower fiber density in both outer
portions n, n' than in the central portion m. Two sheets such as
this are laminated to form a cross. This method is shown in FIG. 12
and then FIG. 3. A string 7 is attached to the laminate in the
central portion thereof in such a way as to allow the string to
protrude in that portion as the rear end, followed by compression
molding. This way a tampon shown in FIG. 10 is obtained. Such a
tampon has an excellent feature that it opens like a parachute due
to swelling thereof when it absorbs menstrual blood, as can be
understood from the process of production, so that menstrual blood
hardly leaks, and that the tampon can be easily pulled out after
service thereof.
Here, consideration will be given to the fiber density of the
tampon. As described above, the tampon according to this invention
is formed by such compression molding as to provide a lower fiber
density in the first part n constituting the front portion thereof
than the fiber density in the second part constituting the rear
portion thereof. Several kinds of absorbent members of tampons as
shown in FIG. 7 were tentatively prepared which differ in the
densities of the first and second parts thereof and the volume
proportion of the first and second parts relative to the whole of
absorbent member of the tampon as shown in Table 1. As to these
absorbent members of tampons, the rates of absorption were
experimentally examined by using the following three kinds of test
liquids.
The testing conditions were as follows.
(1) Method of Ejection of Liquid:
Warm water of 50.degree. C. was ejected through nozzles having a
diameter of 0.16 mm at a pressure of 40 to 80 kg/cm.sup.2. The
distance between nozzles was 0.167 mm.
(2) Size of Tampon: 11 mm in diameter, 50 mm in length
(3) Fiber Used: rayon of 3 deniers and 51 mm
(4) Test Liquids:
[water] aqueous Congo Red solution of 4 cps (25.degree. C.)
[blood A] equine defibrinated blood of 28 cps in viscosity
(25.degree. C.)
[blood B] equine defibrinated blood of 83 cps in viscosity
(25.degree. C.)
(5) Test Method:
A tampon was set in a elastic rubber tube having an internal
diameter of 10 mm. In a state of the tip of the tampon being on the
upper side, 5 g of a test liquid was poured on the tip of the
tampon at a stroke. The time till completion of absorption of the
liquid was measured.
(6) Calculation of Density:
The tampon was separated into two parts at the face where the
density sharply changed. The average densities of the first part
constituting the front portion and the second part constituting the
rear portion, and the overall average density of the absorbent
member of the tampon were calculated.
The test results are shown in Table 1.
TABLE 1
__________________________________________________________________________
Ejection First part Second part Average of Density Proportion
Density Proportion density Rate of absorption (sec.) liquid No.
(g/cm.sup.3) (%) (g/cm.sup.3) (%) (g/cm.sup.3) Water Blood A Blood
B
__________________________________________________________________________
Example of this invention made 1 0.2 50 0.6 50 0.4 3 9 29 2 0.2 40
0.7 60 0.5 3 10 33 3 0.3 50 0.5 50 0.4 3 12 30 4 0.3 50 0.7 50 0.5
4 14 43 5 0.4 60 0.65 40 0.5 4 16 48 6 0.5 40 0.8 60 0.68 5 26 62
Comparative examples not made 7 0.3 50 0.7 50 0.5 4 30 85 8 0.5 50
0.5 50 0.5 5 34 122 9 0.5 40 0.8 60 0.68 6 61 865 10 0.8 50 0.8 50
0.8 7 93 not absorbed*
__________________________________________________________________________
Note *3,600 sec. or more
In Table 1, when the test liquid is water, those not lowered in
fiber density in the first part of the absorbent member of the
tampon as compared with that in the second part thereof (Nos. 8 and
10) as well as those having considerably high fiber densities in
both the first and second parts (Nos. 9 and 10) showed a high rate
of absorption and, hence, looked as if they were excellent as the
absorbent member of the tampon. However, menstrual blood to be
actually absorbed has a high viscosity. Therefore, those having a
high rate of absorption of a high-viscosity liquid such as blood A
or blood B are desired as the absorbent member of the tampon.
As can be seen in a comparison of No. 4 with No. 7 in Table 1, the
absorbent member of the tampon according to the present invention
had a high rate of absorption since the amount of a lubricant
sticking to the fiber was decreased by ejection of a liquid.
Besides, the lowered density in the first part gave a good
influence on the rate of absorption.
The fiber density of the first part of the absorbent member of the
tampon is preferably 0.5 g/cm.sup.3 or lower, more preferably 0.2
to 0.4 g/cm.sup.3. The fiber density of the second part is
adequately 0.5 to 0.8 g/cm.sup.3. The overall average density of
the absorbent member of the tampon is desired to be 0.7 g/cm.sup.3
or lower. An absorbent member of a tampon having an average density
above that value is essentially so slow in absorption of a
high-viscosity liquid such as menstrual blood that it may often
leak along the side of the tampon. On the contrary, when the
average fiber density of not only the first part but also the
second part is as low as, for example, 0.2 g/cm.sup.3 or less, a
high rate of absorption of blood can be secured without use of a
fiber sheet-like material against which a liquid is ejected as in
the present invention. However, such a tampon with a low average
fiber density has a low capacity of absorption and, hence, is
unsatisfactory as a tampon. As a result of some tests, it is
preferred that a volume ratio of the first part to the entire
absorbent member is 30% or larger, more preferably 30 to 70%, most
preferably 40 to 70%. When a volume proportion of proratio of the
first part is less than 30%, the initial rate of absorption of
menstrual blood happens to be slow. On the other hand, when the
volume proportion of the first part exceeds 70%, the capacity of
absorption happens to be comparatively low.
The absorbent member of the tampon according to the present
invention has a lower fiber density in the first part constituting
the front portion than the fiber density in the second part
constituting the rear portion, and a reduced amount of a lubricant
sticking to the fiber. Therefore, the initial rate of absorption of
a high-viscosity liquid such as menstrual blood is so high that the
tampon can absorb menstrual blood without leakage thereof even when
3 to 5 g of menstrual blood is discharged at once. Furthermore,
since the absorbent member of the tampon according to the present
invention comprises a fiber sheet-like material compression-molded
into the absorbent member, which is formed by ejecting a liquid
against a fiber laminate, the proportion of a minute and/or short
fibers contained therein is so low that the amount of the fibers
falling off from the tampon at the time of service thereof is by
far small as compared with those in the case of conventional
absorbent members of tampons.
The absorbent member of the tampon mounted on a so-called
applicator (inserting device) is, of course, included in the scope
of this invention, too.
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